src/scribe/mcp/tools/search.py

@@ -262,6 +262,13 @@ It is an UPPER BOUND per surface: a pull records the door it came
     "no measurement" is not "partial measurement", the same distinction
     `suppression`'s null carries a few paragraphs up.
 
+    A SOURCE SHOWING `calls: 0` WAS RECORDING AND MADE NO CALLS. `sources`
+    lists every source the table has ever held, not only those active in the
+    window, so a surface that stopped firing stays visible rather than
+    disappearing — being absent is reserved for a source that has never
+    recorded at all. Its score fields are null, not zero: the calls are a
+    real observation, the distribution is not one.
+
     `rule_usage_failed: true` means that read failed while the rest of the
     readout stood. The counts are still present so a caller can render, but
     they are zeros meaning "could not find out", not "nothing happened" — do

src/scribe/services/retrieval_telemetry.py

@@ -213,6 +213,15 @@ def _bucket(rows: list) -> dict:
     }
 
 
+# The aggregate row Postgres would have returned for a source with no rows in
+# the window: nothing counted, nothing scored. Positional, matching the SELECT
+# `_bucket` unpacks — calls, zero, cleared, p10, p50, p90, min, max, avg_n,
+# dur, measured, supp_calls, supp_zero. The three counts are 0 because zero
+# calls is a real observation; everything else is None because a distribution
+# nobody sampled has no value, and rendering it as 0.0 would state one.
+_NO_ROWS_IN_WINDOW = [0, 0, 0, None, None, None, None, None, None, None, 0, 0, 0]
+
+
 def _round(v, places: int = 4):
     return None if v is None else round(float(v), places)
 
@@ -375,6 +384,25 @@ async def retrieval_summary(user_id: int | None, *, days: int = 30) -> dict:
                 bucket.update(_coverage(log_complete.get(source), since))
                 out["sources"][source] = bucket
 
+            # A source with rows in the table but NONE in this window would
+            # otherwise be absent from the readout — and absent is exactly how
+            # a source that never existed renders, so a surface that WAS
+            # recording and went silent is unreadable (#3720). That is #2663
+            # one level up: the failure that looks like the correct answer.
+            #
+            # Zero here is a real measurement, not a manufactured one. The
+            # all-time query proves the source was recording, and it made no
+            # calls across a window it fully covers — which is why no
+            # `covers_window` special case is needed: a source whose first row
+            # fell after `since` would have that row IN the window and already
+            # hold a bucket, so anything reaching here began before it.
+            for src, first_row in log_complete.items():
+                if src == "*" or first_row is None or src in out["sources"]:
+                    continue
+                quiet = _bucket(list(_NO_ROWS_IN_WINDOW))
+                quiet.update(_coverage(first_row, since))
+                out["sources"][src] = quiet
+
             # The corpus side, at its own grain. `ambient` mirrors
             # note_usage.usage_for_notes: an ambient surfacing was not a scored
             # CHOICE, so folding it into pull-through would understate it.

tests/test_services_retrieval_telemetry.py

@@ -740,6 +740,62 @@ async def test_coverage_is_per_source_because_the_table_is_older_than_its_arms(
             await s.commit()
 
 
+@pytest.mark.integration
+@pytest.mark.asyncio
+async def test_a_surface_that_went_silent_is_not_the_same_as_one_that_never_ran(
+    _dispose_engine,
+):
+    """#3720 — absent is how "never existed" renders, so it cannot also be how
+    "stopped recording" renders.
+
+    A surface losing its recorder is one of the failures this milestone exists
+    to make visible, and dropping it from the readout is the most complete way
+    to hide it. Zero here is a real measurement: the table proves the source
+    was recording, and it made no calls across a window it fully covers.
+    """
+    from datetime import datetime, timedelta, timezone
+
+    from sqlalchemy import delete
+
+    from scribe.models import async_session
+    from scribe.models.retrieval_log import RetrievalLog
+    from scribe.services.retrieval_telemetry import retrieval_summary
+
+    UID = 990078
+    now = datetime.now(timezone.utc)
+    async with async_session() as s:
+        # Recorded once, well before the window, and never since.
+        s.add(RetrievalLog(
+            user_id=UID, source="auto_inject", result_count=3, top_score=0.81,
+            created_at=now - timedelta(days=60),
+        ))
+        await s.commit()
+
+    try:
+        out = await retrieval_summary(UID, days=7)
+
+        assert "auto_inject" in out["sources"], (
+            "a source with rows in the table but none in the window was "
+            "dropped from the readout — a surface that stopped recording now "
+            "reads exactly like one that never existed"
+        )
+        quiet = out["sources"]["auto_inject"]
+        assert quiet["calls"] == 0
+        # The window IS covered; what was observed across it is nothing.
+        assert quiet["covers_window"] is True
+        # ...but nothing was sampled, so no distribution may be claimed. A
+        # zeroed score would assert a measurement, which is #3311's mistake.
+        assert quiet["top_score"] == {
+            "p10": None, "p50": None, "p90": None, "min": None, "max": None,
+        }
+        assert quiet["suppression"] is None
+        assert quiet["avg_result_count"] is None
+    finally:
+        async with async_session() as s:
+            await s.execute(delete(RetrievalLog).where(RetrievalLog.user_id == UID))
+            await s.commit()
+
+
 @pytest.mark.integration
 @pytest.mark.asyncio
 async def test_a_section_is_complete_only_from_its_latest_contributor(